[Photo by He Guanxin/Provided to China Daily]

Dangdang, China's largest online bookseller, sold 500 million copies in 2015, rising from330million in the previous year. JD.com, another leading online bookseller, sold 200 million copies last year - 12 printed books for every online user on an average.

But in 2014, Chinese read 4.56 copies of offline books on an average, as compared with 4.77 in 2013. While the purchase of offline books went up, people spent at least 30 minutes on an average reading books on smartphones and other devices last year.

Last year's best-seller was the coloring book Secret Garden, according to OpenBook. Dangdang sold some 1.5 million copies.

Other popular titles in 2015 included The Kite Runner by Khaled Hosseini, Unworried Store by Higashino Keigo and Pingfan de Shijie (Ordinary World) by Lu Yao, according to OpenBook.

When the Chinese stock markets hit their highest point of last year, books on investment and finance peaked in sales, according to Dangdang.

Last year, the most popular purchase among Chinese in their 40s and 50s was The Lost Nutriology: Away from Diseases. People born a decade or two later loved Zero to One: Notes on Startups or How to Build the Future, among similar books.

For younger Chinese, the majority of the books they bought were on English and political examinations, the online bookstore says.

The popularity of some Chinese TV series also led to the sale of novels on which they are based, including Faerie Blossom, Nirvana in Fire and Legend of Miyue.